1. Field of the Invention
The invention relates to methods and apparatus for treating an article; and, more particularly, for simultaneously etching a plurality of semiconductor wafers.
As is well known, the impact which modern solidstate electronic components such as transistors and integrated circuits have had upon our society is difficult to overestimate. A central factor contributing to the pervasiveness with which such components have become a part of daily life, is the relatively low cost of such components. The low cost is achieved principally because of batch handling techniques which have been developed for fabricating the components. For example, typically hundreds and often thousands of such components are simultaneously fabricated within and upon the surface of a single semiconductor wafer of substantially circular cross-section.
Techniques for batch handling of pluralities of wafers simultaneously also are significant, not only in reducing cost but also in reducing damage to and contamination of wafers which can be incurred during manual handling of individual ones. Presently, it is conventional to handle a plurality of wafers simultaneously in a slotted carrier having an open face through which the wafers can be inserted into the slots and removed therefrom. Extension of such techniques is a primary motivating factor leading to this invention.
2. Description of the Prior Art
It is known to simultaneously etch a plurality of wafers with one in each of a corresponding plurality of slots and to impart a relative movement between the wafers and the etching solution for providing a more uniform etch. See for example, U.S. Pat. No. 3,607,478 issued Sept. 21, 1971 to K. Henninges et al. Henninges et al. teaches holding the wafers in a carrier which is disposed in the bottom of a vessel containing the desired etching solution. The entire vessel is rocked about a central pivot point to impart a rolling motion of each wafer within its respective slot.
Unfortunately, apparatus of the type disclosed by Henninges et al. is such that the wafers are inserted in the slots manually and individually, thus precluding the economic and other advantages of batch handling. Further, the necessity for moving the entire vessel containing the etching solution causes mechanical drive difficulties and is somewhat dangerous, due to the agitation of the acid or similar dangerous chemical which is used for the etching operation.